/*
 * DBeaver - Universal Database Manager
 * Copyright (C) 2010-2017 Serge Rider (serge@jkiss.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jkiss.dbeaver.model.sql.eval;

import org.apache.commons.jexl2.Expression;
import org.apache.commons.jexl2.JexlEngine;
import org.jkiss.dbeaver.DBException;
import org.jkiss.dbeaver.model.sql.SQLScriptContext;

/**
 * ScriptVariablesContext
 */
public class ScriptEvaluateEngine {

    private final SQLScriptContext scriptContext;
    private final JexlEngine jexlEngine;
    private final ScriptVariablesContext variablesContext;

    private ScriptEvaluateEngine(SQLScriptContext scriptContext) {
        this.scriptContext = scriptContext;
        jexlEngine = new JexlEngine(null, null, null, null);
        jexlEngine.setCache(100);

        variablesContext = new ScriptVariablesContext(scriptContext);
    }

    public Object evaluateExpression(String exprString) throws DBException {
        try {
            Expression expression = jexlEngine.createExpression(exprString);
            return expression.evaluate(variablesContext);
        } catch (Exception e) {
            throw new DBException("Error evaluating expression [" + exprString + "]", e);
        }
    }

    public static ScriptEvaluateEngine getEngine(SQLScriptContext scriptContext) {
        ScriptEvaluateEngine engine = (ScriptEvaluateEngine) scriptContext.getData("evalEngine");
        if (engine == null) {
            engine = new ScriptEvaluateEngine(scriptContext);
            scriptContext.setData("evalEngine", engine);
        }
        return engine;
    }
}
